1. Field of the Invention
This invention relates to a focal point detection system and more particularly to an improvement on a system for displaying the results of focal point detection.
2. Description of the Prior Art
With regard to devices for displaying the focus adjusting state of an image forming lens in an optical system and particularly in an optical apparatus such as a photographic camers, various arrangements have been disclosed. For example, U.S. Pat. No. 3,529,528 discloses a system that uses a meter as a display means, while West German Patent Publication No. 2,537,482 discloses a system that uses LEDs (light emitting diodes) as display means. In the former, focusing state can be displayed at various points such as an in-focus point, defocus points including near-focus and far-focus points and also the degree of such defocus points. These focusing states are not very clearly displayed when presented on a meter. Particularly, in cases where such a display system is applied to a small apparatus such as a camera, the display tends to be affected by the size of the system, camera holding posture, and the like. The display system moreover, is not always suitable for such applications. In the latter case, although the system is capable of displaying in-focus, near-focus and far-focus points, it is incapable of displaying the degree of a defocus state. Therefore, the display becomes critical in the neighborhood of an in-focus point. This makes the latter system difficult to operate.